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Question
An object is kept at a distance of 1m from a lens of power +2D:
- Identify the type of lens.
- Calculate its focal length and distance of the image formed.
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Solution
- The given lens is convex because convex lenses have a positive power.
- P = `1/"f"`
+2 = `1/"f"`
f = +0.50 m
Its focal length is +0.50 m.
Using the relation = `1/"f"=1/"v"-1/"u"`
`1/"v"=1/"f"+1/"u"`
= `1/0.5+ (-1)/1`
= `(2+(-1))/1`
v = 1 m
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